Side walls and roofs, hereinafter referred to as wall assemblies, of industrial buildings are frequently assembled on site in the form of inner and outer facings supported on elongated metal framing members or girts Typically the inner facing is assembled from metal sheets or panels while the outer facing is assembled from either metal or synthetic resin sheets or panels, and slabs of insulating material such as glass fiber batts are disposed between the facings. Heat conduction through the wall assembly is reduced by the pressure of the insulation, but in the typical construction there are various heat-flow paths through the assemblies formed by internal heat-conducting metal mounting means in thermal contact with metal components of the assembly. As an example, in one form of conventional wall construction there are inner sheet metal panels attached by self-tapping screws to the outside of a plurality of elongated steel framing members or main girts, the panels having interlocking flanges at their edges which form a series of ribs. Lighter-weight framing members or sub-girts are then attached to this inner wall structure, and finally the outer facing in the form of metal or resin siding panels are attached to the sub-girts The sub-girts lie against the ribs on the inner panels, with gaskets placed therebetween, and are secured in place by self-tapping screws which pass into the ribs and/or through the inner panels into the main girts. The metal-to-metal contact of the screw threads with the inner panels and/or with the main girts inherently provide heat conduction paths.
The present invention provides a wall assembly in which heat conduction paths between inner and outer metal components are avoided by the use of special clamp-type mounting assemblies having opposed relatively non-conducting clamping surfaces which tightly engage one of the metal components without the aid of screws or other fasteners which would effect metal-to-metal contact. A preferred form of mounting assembly includes a metal clip having a body portion which can be attached to one wall component by any conventional means such as a screw and end portions each of which can be folded inwardly toward the body portion. The clips are initially constructed with their ends only partially folded. During assembly a special tool is used to force the ends into their final clamping position. The thermal insulation is preferably in the form of small blocks of insulating material clamped between the clip ends and the wall component, the blocks being first positioned on the wall component and then clamped in place by deformation of the clip ends. In an alternate construction the blocks may be secured to the clips before the clip ends are deformed to their final positions.
The clip assemblies may also be designed as a releasable fastener which will separate from the wall component which is clamped by the deformable clip ends in the event of an explosion or other pressure rise in the building. In this embodiment the clip ends are constructed with reduced rigidity so that the ends will unfold if excessive outward pressure is applied to the outer wall components.
In one form of conventional construction the wall component to which the special clip is clamped is an elongated sheet metal framing member which is transverse cross-section is hat-shaped in the sense that the cross-section exhibits a central channel and a lateral flange projecting from each wall of the channel at the open end of the latter. In the assembled position the body of the clip spans the open end of the channel and overlies one surface of each lateral flange. As part of the assembly method each end portion of the clip is folded toward the body thereby clamping each of the lateral flanges of the framing member between the clip body and one of the end portions of the clip.